The present invention generally relates to a valve for controlling the flow of fluid and more particularly pertains to a valve for simultaneously controlling the distribution and flow of an automobile's coolant through multiple flow paths.
Water-cooled internal combustion engines that are used in automobiles rely on a fluid to carry excess heat from the engine to an external heat exchanger commonly referred to as the radiator. Such coolant is continuously recirculated through the engine until its temperature exceeds a preselected level at which point a portion of the flow is routed through the heat exchanger. The flow to the radiator is continuously adjusted in order to maintain the temperature of the coolant within a desired range. The heat carried by the fluid is also used to heat the interior of the automobile whereby a portion of the circulating coolant is routed through a second heat exchanger positioned so as to heat air that is directed into or recirculated within the passenger compartment.
The distribution of the flow of coolant that is generated by an engine-driven water pump is typically controlled by two separate components, namely a radiator thermostat and a heater valve. Heretofore used thermostats typically rely on a mechanism that causes the force generated by the expansion of mass of wax-like material to overcome the bias of a spring to open a valve wherein the wax-like material expands as a function of temperature. The entire device is immersed in the flow of coolant and is positioned and configured so as to block off the flow of coolant to the radiator when the valve is closed. While the valve is in its closed position, the coolant continues to circulate but is forced to bypass the radiator and is redirected back into the engine's water passages. A number of disadvantages are associated with this type of configuration including, but not limited to, the fact that the bypass flow path remains open at all times and that a portion of the flow of coolant therefore always bypasses the radiator even if maximum cooling is called for. Additionally, the positioning of the thermostat directly in the flow path of the coolant poses an impediment to the flow of coolant and thereby compromises the efficiency of the cooling system while the failure of the opening mechanism typically results in the thermostat remaining in its closed configuration which can quickly lead to engine damage. Another disadvantage inherent in heretofore used thermostat configurations is the fact that the device can necessarily only respond to the temperature of the coolant rather than directly to the temperature of the engine, let alone the anticipated cooling needs of the engine. The engine temperature may therefore not necessarily be optimized for a variety of conditions, which may result in decreased fuel efficiency and increased exhaust emissions.
Heater valves are typically positioned so as to direct a portion of the flow of coolant to a heater core positioned within the HVAC system of the automobile. Early heating systems included a valve that was simply actuated by a cable extending from a lever positioned in the interior of the automobile. Many modern systems employ computer controlled servo operated valves, wherein the valve position is either modulated so as to control the temperature of the heater or subject to either a fully open or fully closed position wherein air heated by the heater is subsequently mixed with cooled air to regulate the temperature within the passenger compartment.
A difficulty associated with this heretofore approach toward controlling the flow and distribution of coolant is inherent in the fact that, in effect, two independently operating systems are affecting the temperature of a common coolant. A change in the demand for heat within the passenger cabin will effect the temperature of the coolant as will the position of the thermostat. A change in one will necessarily induce a change in the other and without a common control system, the temperature may tend to fluctuate and dither. Variations in engine load, especially in for example in stop-and-go traffic will introduce even more fluctuation as the heat fed into the system will additionally be subject to variation. Increasingly strict emission regulations and demands for higher fuel efficiencies require the engine to operate in narrower temperature ranges which requires a more precise control of coolant temperature. An improved cooling system is needed with which coolant temperature and hence engine and heater temperature can be more precisely controlled.